//! Book keeping for keeping diagnostics easily in sync with the client.
pub(crate) mod to_proto;

use std::mem;

use ide::FileId;
use ide_db::FxHashMap;
use itertools::Itertools;
use nohash_hasher::{IntMap, IntSet};
use rustc_hash::FxHashSet;
use stdx::iter_eq_by;
use triomphe::Arc;

use crate::{global_state::GlobalStateSnapshot, lsp, lsp_ext, main_loop::DiagnosticsTaskKind};

pub(crate) type CheckFixes = Arc<IntMap<usize, IntMap<FileId, Vec<Fix>>>>;

#[derive(Debug, Default, Clone)]
pub struct DiagnosticsMapConfig {
    pub remap_prefix: FxHashMap<String, String>,
    pub warnings_as_info: Vec<String>,
    pub warnings_as_hint: Vec<String>,
    pub check_ignore: FxHashSet<String>,
}

pub(crate) type DiagnosticsGeneration = usize;

#[derive(Debug, Default, Clone)]
pub(crate) struct DiagnosticCollection {
    // FIXME: should be IntMap<FileId, Vec<ra_id::Diagnostic>>
    pub(crate) native_syntax: IntMap<FileId, (DiagnosticsGeneration, Vec<lsp_types::Diagnostic>)>,
    pub(crate) native_semantic: IntMap<FileId, (DiagnosticsGeneration, Vec<lsp_types::Diagnostic>)>,
    // FIXME: should be Vec<flycheck::Diagnostic>
    pub(crate) check: IntMap<usize, IntMap<FileId, Vec<lsp_types::Diagnostic>>>,
    pub(crate) check_fixes: CheckFixes,
    changes: IntSet<FileId>,
    /// Counter for supplying a new generation number for diagnostics.
    /// This is used to keep track of when to clear the diagnostics for a given file as we compute
    /// diagnostics on multiple worker threads simultaneously which may result in multiple diagnostics
    /// updates for the same file in a single generation update (due to macros affecting multiple files).
    generation: DiagnosticsGeneration,
}

#[derive(Debug, Clone)]
pub(crate) struct Fix {
    // Fixes may be triggerable from multiple ranges.
    pub(crate) ranges: Vec<lsp_types::Range>,
    pub(crate) action: lsp_ext::CodeAction,
}

impl DiagnosticCollection {
    pub(crate) fn clear_check(&mut self, flycheck_id: usize) {
        if let Some(it) = Arc::make_mut(&mut self.check_fixes).get_mut(&flycheck_id) {
            it.clear();
        }
        if let Some(it) = self.check.get_mut(&flycheck_id) {
            self.changes.extend(it.drain().map(|(key, _value)| key));
        }
    }

    pub(crate) fn clear_check_all(&mut self) {
        Arc::make_mut(&mut self.check_fixes).clear();
        self.changes
            .extend(self.check.values_mut().flat_map(|it| it.drain().map(|(key, _value)| key)))
    }

    pub(crate) fn clear_native_for(&mut self, file_id: FileId) {
        self.native_syntax.remove(&file_id);
        self.native_semantic.remove(&file_id);
        self.changes.insert(file_id);
    }

    pub(crate) fn add_check_diagnostic(
        &mut self,
        flycheck_id: usize,
        file_id: FileId,
        diagnostic: lsp_types::Diagnostic,
        fix: Option<Box<Fix>>,
    ) {
        let diagnostics = self.check.entry(flycheck_id).or_default().entry(file_id).or_default();
        for existing_diagnostic in diagnostics.iter() {
            if are_diagnostics_equal(existing_diagnostic, &diagnostic) {
                return;
            }
        }

        if let Some(fix) = fix {
            let check_fixes = Arc::make_mut(&mut self.check_fixes);
            check_fixes.entry(flycheck_id).or_default().entry(file_id).or_default().push(*fix);
        }
        diagnostics.push(diagnostic);
        self.changes.insert(file_id);
    }

    pub(crate) fn set_native_diagnostics(&mut self, kind: DiagnosticsTaskKind) {
        let (generation, diagnostics, target) = match kind {
            DiagnosticsTaskKind::Syntax(generation, diagnostics) => {
                (generation, diagnostics, &mut self.native_syntax)
            }
            DiagnosticsTaskKind::Semantic(generation, diagnostics) => {
                (generation, diagnostics, &mut self.native_semantic)
            }
        };

        for (file_id, mut diagnostics) in diagnostics {
            diagnostics.sort_by_key(|it| (it.range.start, it.range.end));

            if let Some((old_gen, existing_diagnostics)) = target.get_mut(&file_id) {
                if existing_diagnostics.len() == diagnostics.len()
                    && iter_eq_by(&diagnostics, &*existing_diagnostics, |new, existing| {
                        are_diagnostics_equal(new, existing)
                    })
                {
                    // don't signal an update if the diagnostics are the same
                    continue;
                }
                if *old_gen < generation || generation == 0 {
                    target.insert(file_id, (generation, diagnostics));
                } else {
                    existing_diagnostics.extend(diagnostics);
                    // FIXME: Doing the merge step of a merge sort here would be a bit more performant
                    // but eh
                    existing_diagnostics.sort_by_key(|it| (it.range.start, it.range.end))
                }
            } else {
                target.insert(file_id, (generation, diagnostics));
            }
            self.changes.insert(file_id);
        }
    }

    pub(crate) fn diagnostics_for(
        &self,
        file_id: FileId,
    ) -> impl Iterator<Item = &lsp_types::Diagnostic> {
        let native_syntax = self.native_syntax.get(&file_id).into_iter().flat_map(|(_, d)| d);
        let native_semantic = self.native_semantic.get(&file_id).into_iter().flat_map(|(_, d)| d);
        let check = self.check.values().filter_map(move |it| it.get(&file_id)).flatten();
        native_syntax.chain(native_semantic).chain(check)
    }

    pub(crate) fn take_changes(&mut self) -> Option<IntSet<FileId>> {
        if self.changes.is_empty() {
            return None;
        }
        Some(mem::take(&mut self.changes))
    }

    pub(crate) fn next_generation(&mut self) -> usize {
        self.generation += 1;
        self.generation
    }
}

fn are_diagnostics_equal(left: &lsp_types::Diagnostic, right: &lsp_types::Diagnostic) -> bool {
    left.source == right.source
        && left.severity == right.severity
        && left.range == right.range
        && left.message == right.message
}

pub(crate) enum NativeDiagnosticsFetchKind {
    Syntax,
    Semantic,
}

pub(crate) fn fetch_native_diagnostics(
    snapshot: &GlobalStateSnapshot,
    subscriptions: std::sync::Arc<[FileId]>,
    slice: std::ops::Range<usize>,
    kind: NativeDiagnosticsFetchKind,
) -> Vec<(FileId, Vec<lsp_types::Diagnostic>)> {
    let _p = tracing::info_span!("fetch_native_diagnostics").entered();
    let _ctx = stdx::panic_context::enter("fetch_native_diagnostics".to_owned());

    let convert_diagnostic =
        |line_index: &crate::line_index::LineIndex, d: ide::Diagnostic| lsp_types::Diagnostic {
            range: lsp::to_proto::range(line_index, d.range.range),
            severity: Some(lsp::to_proto::diagnostic_severity(d.severity)),
            code: Some(lsp_types::NumberOrString::String(d.code.as_str().to_owned())),
            code_description: Some(lsp_types::CodeDescription {
                href: lsp_types::Url::parse(&d.code.url()).unwrap(),
            }),
            source: Some("rust-analyzer".to_owned()),
            message: d.message,
            related_information: None,
            tags: d.unused.then(|| vec![lsp_types::DiagnosticTag::UNNECESSARY]),
            data: None,
        };

    // the diagnostics produced may point to different files not requested by the concrete request,
    // put those into here and filter later
    let mut odd_ones = Vec::new();
    let mut diagnostics = subscriptions[slice]
        .iter()
        .copied()
        .filter_map(|file_id| {
            let line_index = snapshot.file_line_index(file_id).ok()?;
            let source_root = snapshot.analysis.source_root_id(file_id).ok()?;

            let config = &snapshot.config.diagnostics(Some(source_root));
            let diagnostics = match kind {
                NativeDiagnosticsFetchKind::Syntax => {
                    snapshot.analysis.syntax_diagnostics(config, file_id).ok()?
                }
                NativeDiagnosticsFetchKind::Semantic => snapshot
                    .analysis
                    .semantic_diagnostics(config, ide::AssistResolveStrategy::None, file_id)
                    .ok()?,
            };
            let diagnostics = diagnostics
                .into_iter()
                .filter_map(|d| {
                    if d.range.file_id == file_id {
                        Some(convert_diagnostic(&line_index, d))
                    } else {
                        odd_ones.push(d);
                        None
                    }
                })
                .collect::<Vec<_>>();
            Some((file_id, diagnostics))
        })
        .collect::<Vec<_>>();

    // Add back any diagnostics that point to files we are subscribed to
    for (file_id, group) in odd_ones
        .into_iter()
        .sorted_by_key(|it| it.range.file_id)
        .group_by(|it| it.range.file_id)
        .into_iter()
    {
        if !subscriptions.contains(&file_id) {
            continue;
        }
        let Some((_, diagnostics)) = diagnostics.iter_mut().find(|&&mut (id, _)| id == file_id)
        else {
            continue;
        };
        let Some(line_index) = snapshot.file_line_index(file_id).ok() else {
            break;
        };
        for diagnostic in group {
            diagnostics.push(convert_diagnostic(&line_index, diagnostic));
        }
    }
    diagnostics
}
